Russian forces launched three strikes on Friday on Kharkiv, Ukraine's second-largest city, injuring 15 people, including three children, Mayor Ihor Terekhov said.

Late on September 20, Russian troops once again launched guided bombs on Kharkiv. Three districts of the city came under attack, with 15 people injured, according to the Kharkiv Regional Prosecutor's Office and Mayor of Kharkiv Ihor Terekhov.

According to the Kharkiv Oblast Prosecutor's Office, Russian Su-34 jets launched three guided bombs from across the border in Russia's Belgorod Oblast.

About 130 U.S. soldiers are returning to their bases after being deployed to a remote Alaska island amid a spike in Russian military activity off the western reaches of the U.S.

The actions follow a series of Russian air operations that skirted Alaskan airspace and as Russian and Chinese warships conducted joint exercises across the Pacific.

The U.S. military has stationed around 130 soldiers and mobile rocket launchers on an uninhabited island in the Aleutian chain in western Alaska. This move follows increased activity by Russian and Chinese military forces near U.